1. Field of the Invention
This invention relates generally to fasteners of different kinds and relates particularly to fasteners which can be driven into metallic structures or materials by means of a blow from a manually operated hammer or by a nailing gun.
2. Description of the Prior Art
Heretofore many efforts have been made to provide fasteners for driving into various types of base material with most of the fasteners being applied to relatively soft material such as wood and the like and with some fasteners being applied to metallic materials. In most instances in which the fastener is applied to metallic material, a hole is first provided in the material after which the base material is tapped or provided with threads to receive a machine screw or the like.
Some efforts have been made to provide fasteners which can be driven into metallic structures; however, in most instances these fasteners have required an explosive charge for driving the same and accordingly such fasteners have been relatively expensive to produce and also have been dangerous in use due to flying chips caused by the explosive charge as well as the possibility of premature explosion or firing of the charge before the fastener is in position to penetrate the metallic structure.
Additionally, some efforts have been made to provide a fastener which can be driven into metallic structures by means of a manually operated hammer or the like, such as my previous U.S. Pat. No. 4,004,483; however, these prior art structures have been generally cylindrical and may be provided with screw threads so that it was necessary to make the structures by means of an automatic screw machine or the like. Substantially all of these structures have had a tendency to rotate within the metallic structure after they had been applied, particularly when a torsional force was applied such as by a nut or the like.
Some additional examples of prior art which can be driven into metal are the French Pat. No. 1,099,241, British Pat. Nos. 732,203 and 757,560. Other examples of the prior art which include fasteners having recesses into which material is received to resist withdrawal are shown by the U.S. Pat. No. DE. 29,283 to Sweeney which discloses a nail, and Austrian Pat. No. 173,100 which discloses a push-point having a pair of recesses into which wood or other relatively soft material may be received.